German Patent Application P 33 31 840.9 (corresponding to U.S. application Ser. No. 643,508, filed on the same day as the present application) relates to a nozzle for mixing at least two flowable reaction components comprising a housing; component supply pipes leading into the housing; a housing bore arranged in the housing having a co-axial outlet channel in its end face; at least one needle casing which is guided co-axially in the housing bore; an injection needle which is guided co-axially in the needle casing; a first chamber located between the wall of the housing bore and the needle casing with one of the component supply pipes opening into said first chamber; a second chamber arranged between the needle casing and the injection needle with another component supply pipe opening into said second chamber; wherein in the closed position, said injection needle forms a tight fit with the internal end face of the needle casing, and the external end face of said needle casing forms a tight fit with the internal end face of the housing bore; and wherein in the open position, said injection needle frees a co-axial nozzle opening of the needle casing and an opening is formed between the external end face of the needle casing and the internal end face of the housing bore. The injection needle is provided with a co-axial plug, the cross-sectional shape and size of which is adapted to that of the nozzle opening of the needle casing and that of the outlet channel and which, in the closed state fills the outlet channel up to the outlet. A forced control is provided for the injection needle and the needle casing at the other end thereof.
In the above described nozzle, a component is supplied through the central opening and further components are supplied through concentric annular gaps.
The sealing surfaces which are provided for the tight fits have to be made extremely accurately to prevent any leakage in the closed state, because each of the components is under pressure around the sealed annular nozzle gap. If the needle casings become slightly out of true, the sealing surfaces warp and cause the tight fits to leak. A further disadvantage of this nozzle is that a further needle casing must generally be provided for each additional component above two reaction components.
Thus, an object of the present invention is to improve the above described nozzle so that the risk of leakage caused by the tight surfaces becoming out of true is reduced and so that in the case of the supply of more than two components, only one needle casing or a reduced number of needle casings is required.